Method of making piston-rings



G. H. BLETTNER. METHODOF MAKING PISTON RINGS. I APPLICATI ON HLED MAY a. 1911. 1 328 414. I" Patented Jan. 20, 1920.

2 SHEETS-SHEET ziisfiitwncj G. H. BLETTNER.

METHOD OF MAKING PISTON RINGS. APPLICATION FILED MAY 5. I917.

' 1,328,414. Patented Jan. 20,1920.

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, of the city of Chicago,

lTED STTES Pd hlhl'i GEORGE E. BLETTNER, OF CHICAGO, ILLT N OIS.

METHOD or MAKING PISTON-RINGS.

Application filed May 5, 1917.

- Making Piston-Rings, of which the followmg is a specification.

My invention relates to a new and improved method of making piston rings, and this application is a continuation 111 part of my. applications Serial No. 116,909, filed Serial No. 131,567, filed November, 15, 1916.

The object of my invention 15 to provide a new and improvedmethod whereby piston rings may be economically manufactured and made to fit accurately.

Another oh' ct of my invention is to reproduce piston rings from a pattern or telnplet, the form of which is obtained by using 'or separator and serves to rings.

a resilient split ring which is compressed and shaped and which upon its release assumes the expanded form owing to its own 25 resiliency and without the use of an insert give the proper form in which rings should be reproduced to fit accurately.

A further object of my invention is to use a properly formed split ring expanded by its own resiliency and make patterns therefrom which are used in reproducing other My invention also has other important objects which will appear from the following specification and the accompanying drawings, in which I have described and illustrated my invention in a preferred form.

011 the drawings:

Figure 1 is a side view of an ordinary split ring utilized in carrying on the method of manufacture,

Fig. 2, a View of said ring sprung into position of and dressed or shaped for use,

Fig. 3, a perspective view of the joint formed of the split in the ring,

Fig. 4, a side View of the ring illustrated in Figs. 1 and 2, but shown in the position it assumes when it springs to substantially original form after being shaped and with a "temple-t fitted thereto,

Fig. 5, a view of the templet detached,

Fig. 6, a top plan View of a gated pattern for forming the ring blanks,

Fig. 7, an enlarged section taken on line 7-4 of Fig.6,

Specification of Letter Patent.

Patented Jan. 20, 1920.

Serial No. 166,551.

Fig. 8, a side view of a ring blank formed from the pattern illustrated in Figs. 6 and 7,

Fig. 9, a side view of a ring completed ready for use,

Fig. 10, an enlarged view of the joint at the split of the ring.

In making piston rings it is necessary that they must be constructed to uniformly engage the inner surface of the cylinder and fit thereagainst with a high degree of accuracy, and it is desirable to make them of uniform thickness so as to evenly fill the groove in the piston with which they are used. The 'prererred piston rings are cast in an imperfect ring shape and have a sec tion cut out thereof so that the ring may be contracted to substantially the size re quired in use and the outer face is ma chined in the contracted condition to the size of the cylinder. It is preferable to retain the skin resulting from the molding, on the inner face of the ring and merely smooth it up, for the sake of economy of manufacture and particularly as it results in a tough ring and it is necessary in order to secure a ring that will compress into a perfect circle and uniformly engage the walls of the cylinder that the pattern must be accurately made so that when the section is cut out and the ring compressed a ring of uniform thickness and adapted to uniformly engage the walls of the cylinder will result.

In an effort to accomplish this result, rings have been heretofore made from a pattern obtained by turning down or otherwise making a ring of the size of the compressed ring, after which it is split and the ends forced apart and a section ing. an imperfect circular which rings are cast. have a section cut out corresponding to the section inserted in the pattern after which the gapped ring is compressed and turned down in the compressed condition.

The formation of the pattern, however. by forcing the ends of the pattern ring apart and insertion of the section causes a distortion of the ring and consequently an imperfect casting, which when turned down does not fit uniformly against the wall of the cylinder. The effect of such forcible separation is similar to that which takes place if a long thin rod be bent in a U-shape like a hair pin with a pair of parallel arms and has the outer ends forced apart. The'armswill how inwardly and a similar distorting strain u as a.)

inserted therein formlit ring when the ends are onsequently the ring cast from such a pattern does not compress uniformly and does not turn down properly and the finished ring lacks the uniform engage ment against the wall of the cylinder which is so very essential in a perfect ring.

In my invention I use a resilient ring which is compressed and turned down to the applied to the s forced apart.

.proper size while compressed and which is expanded by its own resilience when released to the form required for the pattern, and I thereby avoid distortion of the ring and con I split with overlapping portions 11 having .being e projections 12 fitted within recesses 13, as indicated. This ring .is sprung or forced into position of use and the inner and outer surfaces thereof are dressed or cut in a lathe until each the desired size, such a ring so cut or shaped being illustrated in Fig. 2. Then the ring is permitted to expand or spring to its original position as illustrated in Fig. #1, and the ring thus freely expanded by its own resiliency and without the customary forcing apart, is used as a templet to make a form or templet to be used in making pattern rings to be used in making other rings. This templet consists of a plate or disk 1-1:, which is carefully shaped so that the periphery thereof fits accurately-the inner contour of the freely expanded ring or so that the ring in the form assumed by the free expansion thereof accurately fits on the periphery of the tem let, the shaping of the templet ected in any suitable manner, and this templet is used in the formation of ring blanks for the manufacture of the rings on a large scale.

In the method of procedure at present utilized and illustrated in the drawings, the

- templet 14 is utilized for shaping the contour of brass ring blank portions 15. which consist simply of slices or cuts of brass tubing of the proper size compressed and shaped about the templet into proper form, after which they are removed and riveted to a metallic backing plate or follow-board 16. Eight of these ring blank patterns are thus formed and secured in place, said patterns being arranged in groups of four gated together by gates 17 for convenience in casting a plurality of the ring blanks at a single operation. as will be readily understood by those skilled in the art. One of the ring blanks produced from this pattern is illusis a perfect cylinder and of.

trated in Fig. 8 and has substantially the form of the ring illustrated in Fig. 4, and has therefore the form of a freely expanded piston ring which, when properly cut out and finished and compressed, is the exact size and shape for use. The split in this ring blank is formed in any usual or desired manner to produce the overlapping portions 11 and theprojecti'ons 12.- However, the recesses 13 are formed with their outer walls cut to the normal length of radius of the ring but with the centers h and i, slightly offset upwardly and outwardly from the normal. center of the ring, as illustrated in Fig. 9. By this arrangement the ring will be given an inner and outer contour which,

when the ring is sprung into the position indicated in Fi 2, will approximate the true and desire shape of the ring, since its contour is based upon the contour assumed by the ring when in use. .Vhen thus sprung into position of use, the centers 71- and i move inwardly and downwardly to substantially the normal center 0 of the ring so that the outer surfaces of the recesses 13,

when in actual use, assume positions on the true curvature .of the ring, thus greatly fav cilitating the formation and maintenance of a tight seal at the split. The outer surfaces of the projections 12 are dressed to substantially the same curvature as the outer walls of the recesses 13 so as to form a surface fit between the two.

In case it is desired to utilize a pot casting, or a casting in tubular form and obtain the ring blanks therefrom by merely slicing or cutting off sections thereof, as is frequently done, the templet 1- or other form which corresponds to the form assumed by a ring freely expanded by its own resiliency, may be utilized in a lathe for the purpose as a guide for the tools for cutting the interior and exterior surface of such a casting, thus providing ring blanks having the desired preliminary contour.

The rings thus produced and obtained have an interior contour closely approximating the desired one so that no additional cutting or dressing is required for the inner contours of the rings. The outer contours of the rings. where an exact fit is essential, are nicely dressed in the usual manner to obtain a perfect lit in the cylinder. Thus, it will be observed. that rings having a nice and perfect fit in the cylinder, and a niceand perfect seal at the split may be produced without the necessity of dressing the inner contours thereof, and they may therefore be produced with great economy and are highly efficient in use.

\Vhile I have illustrated and described the preferred form of construction and method of procedure for carrying my invention into effect. these are capable o variation and modification within the scope of the apturning said ring contour of said ring;

ended claims. I, therefore, do not wish to e limited to the precise details of construction set' forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

1. The "method of making piston rings which consists in forming the rings from a pattern having the non-circular contour of an inherently expanded split ring which has been shaped in the required form while contracted.

2. The method of which consists in making a solid ring having the non-circular -form of a relaxed, inher-' ently expansible split ring which has been shaped in true circular form while compressed, then splitting the solid ring at the point corresponding to that of such split ring and forming the resultant ends so as to permit compression of the ring to true circular form and to provide'overlapping per-.-

tions when so compressed.

3. The method of making piston rings which consists in making a pattern having the non-circular form of a relaxed inherently expansible split ring which has been shaped in true circular form while com-- pressed, then making a casting from said pattern and then providing the casting with ends suitably formed to permit compression of the ring to true circular'form and to overlap when so compressed.

4. The method of making piston rings Which consists in compressing a split ring into approximately the desired form; shaping said ring to substantially true form; re-

turning said ring to substantially original form; shaping a templet to fit the inner utilizing said templet in the production of a similarly shaped ring blank; and cutting a split in' said ring blank, forming projections at each side of said split and a corresponding recess in each side to receive the projection on the other, the outer walls of said recesses being out substantially on arcs having their centers ofiset from the normal center of the ring, substantially as described.

5. The method of making pistonrings which consists in compressing a split ring into approximately the desired form; shaping said ring to substantially true form; re to substantially original form; shaping a templet to lit the inner contour of said ring; utilizing said templet in the production of a similarly shaped ring pattern; utilizing said pattern to produce making piston rings.

a ring blank; and cutting a split in said ring blank, forming projections at each side of said split and a corresponding recess in each side to receive the the outer walls of substantially on arcs having their centers offset from the normal center of the ring, substantially as described.

6. The method of making piston rings which consists in compressing a split ring pro ection on the other, said recesses being cut into approximately the desired form; shapmg said ring to substantially true form; returning said ring to substantially original form; shaping a templet to fit the inner-contour of said ring; utilizing said templet in the production of a similarly shaped ring blank; and cutting a split in said ring blank, forming projections at each side-of said split and a corresponding recess in each side to receive the projection on the other, the outer walls of said recesses and the outer surfaces of said projections being cut substantially on arcs having their centers offset from the normal center of the ring, substantially as described.

, 7. The method of making piston rings which consists in compressinga split ring into approximately the desired form; shaping, said ring to substantially. true form; returning said ring to substantially original form; shaping a templet to fit the inner contour of said ring; utilizing said templet in the production of a similarly shaped ring pattern; utilizing said pattern to produce a ring blank; and cutting a split in said ring blank, said split and a corresponding recess in each side to receive the projection on the other, the outer walls of said recesses and the outer surfaces of said projections being cut substantially on arcs having their centers offset from the normal center of the ring, substantially as described.

8. The method of making piston rings which consists in compressing a resilient normally expanded split ring into approximately the desired form, then shaping the ring in true circular form in the compressed condition, then shaping a temple-t to fit said ring when relaxed and expanded through its own resiliency,

or forming similarly shaped rings.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

GEORGE H. BLETTNER. Witnesses:

Josnoa R. H. Porrs, B. G. RICHARDS.

forming pro ections at each side of 

